Electrical contact assembly for use in electron discharge devices



Jupe 29, 19 4 K. M. MCLAUGHLIN ELECTRICAL CONTACT ASSEMBLY FOR USE IN ELECTRON DISCHARGE DEVICES Filed Jan. 16, 1942 a Q Q & Twl

I ayghlin. wmwaw ATT DR N EY Patented June 29, 1943 ELECTRICAL CONTACT ASSEMBLY FOR USE IN ELECTRON DISCHARGE DEVICES Kenneth M. McLaughlin, Summit, N. 1., assignor to Radio Corporation oi America, a corporation oi Delaware Application January 16, 1942, Serial No. 426,960

7 Claims. (Cl. 250-275) My invention relates to current carrying leads and contacts and more particularly to leads and contacts suitable for and in combination with electron discharge devices such as cathode ray tubes and the like.

In many electron discharge devices and particularly in cathode ray tubes it has been found desirable to make an electrical connection to some individual electrode element, inside the tube, at a point on the envelope wall other than at the stem. The conventional method of making such a connection has been to seal a wire of suitable material to a tubulation in the bulb wall.- A metal terminal is then cemented to the bulb and soldered to the wire to provide a suitable contact.

A serious disadvantage of this design has been, that in projecting beyond the surface of the bulb, the contact is exposed to bumps and knocks. Breakage of the contact in processing or during use generally results in the loss of the complete tube. The projection of these contacts has also prohibited their use in places such as the neck of a cathode ray tube where it would be desirable to bring out deflection plate leads, but where it is also necessary to slide a close fitting yoke along the neck. When wire leads in a recess were tried for this purpose it was found that the wire did not provide a secure contact of suiilcient area. Metal cups sealed into the bulb wall with the concave side out were also tried but the glassto-metal seal failed when suflicient pressure to make a good electrical contact was applied near the seal. In addition such contacts are exposed and may be touched by the user so that there is considerable danger during the operation of the tube particularly when such leads are energized at high potentials.

It is an object of my invention to provide an improved form of current-carrying conductor and associated structure for making connection through the enclosing wall of an electron discharge device such as a cathode ray tube. It is another object to provide an improved currentcarrying conductor which does not extend beyond the bulb wall and to which an electrical contact member may be attached without subjecting the bulb wall to stresses which might produce failure of the bulb wall. It is a further object to provide a tube and method of manufacture wherein electrode structure may be assembled without the necessity of sealing currentcarrying conductors through the wall of the tube after the assembly of the structure, and it is a still further object to provide a current-carrying conductor in combination with cathode ray tubes having deflection plates wherein the deflection plates may be resiliently supported from the contact member.

In accordance with one teaching of my invention, I avoid the above disadvantages possessed of the prior art by providing a cup-shaped conducting member sealed in the bulb wall envelope and equipped with a contacting member which is attached thereto without stressing the conducting member and contained wholly within the cup-shaped member so that it is protected from mechanical shock and breakage and to which a power supply "or other electrical connection may be made. These and other objects, features and advantages of my invention will be apparent to those skilled in the art upon consideration of the following description and the accompanying drawing in which:

Figure 1 shows a cathode ray tube in partial longitudinal section having. electrical contact members made in accordance with my invention, and

Figures 2 and 3 show two embodiments of contact members suitable for use in the tube shown in Figure l. 4

Referring to Figure 1, I have shown a cathode ray tube having an envelope or bulb I of conventional form including a cylindrical neck portion 2 containing electrodes mounted on a glass stem or press to form and deflect an electron beam over a target structure such as a luminescent screen target on the tube end wall 3. More particularly, the electron beam forming structure 4 and beam deflection structure 5 ar formed in a single unit on a stem or press 00 that the entire assembly during process of manufacture may be slipped within and sealed to the neck portion 2. The electron beam forming structure may be of any conventional type and comprises a cathode, beam intensity control electrode and any desired plurality of anode electrodes to develop an electron beam which is directed toward and focused upon the target on the end wall 3. The deflection structure 5 is preferably supported in common with the beam forming structure such as by mounting the defiection plates forming this structure upon longitudinally extending insulating supports 6. One set of deflection plates such as the plates I may -be used in combination with magnetic means to deflect the electron beam over the target surface, although I have shown an additional set of plates 8 positioned to deflect the beam in a direction perpendicular to the deflection produced by the deflection plates 1.

From the drawing of Figure 1 it will be apparent that it is necessary to energize the deflection plates I and 8, and while this may be done by passing the leads longitudinally of the neck section and through the stem or press, such a structure is unsatisfactory where relatively high potentials with respect to the potentials of other electrodes must be applied to the deflection plates. In addition as indicated above, it is quite difllcult to pass conductive leads through the wall of the neck portion 2 after the structures 4 and 5 are inserted within the neck portion and even if the construction is used, such leads offer no support to the electrode structure.

Therefore in accordance with my invention, I provide cup-shaped conducting members 9 forming a portion of the wall of the neck section, these members being substantially flush with the exterior surface of the neck portion and extending within the inner surface thereof. In addition, I provide resilient members III which are preferably attached directly to the deflection plates I and 9 so that upon slipping the electrodes supported by the longitudinal members 6 into the neck section the resilient springs Ill slide along and make contact with the cup-shaped members 9. It is important that each of the spring members Ill be provided with equal tension so that when compressed against the members 9, they provide good electrical contact therebetween and support the electrode structure centrally of the neck portion 2. The members 9 should be posi tloned longitudinally of the neck section 2 so as to facilitate contact with the spring members l0 when the mount assembly is in the desired position and are preferably positioned to the rear of the deflection plates, that is, further removed from the end wall 3 than are the associated deflection plates. It will be appreciated from an inspection of Figure 1 that my new contact allows full use of substantially the entire inside diameter of the neck section 2 for enclosing the electrode structure. Furthermore, the outside diameter of the envolepe is not increased so that a more efllcient deflection yoke may be slipped over the neck section to provide additional deflection of the electron beam or, in the case only one pair of deflection plates is used, to provide the second deflection coordinate.

Referring to Figures 2 and 3, I have shown two forms of the contact members wherein similar parts are similarly referenced including the cupshaped member 9 sealed to the bulb I and forming a small portion of its wall, the recessed surface extending outwardly of the bulb. While electrical contact might be made to the member 9 such as by spring fingers fitting under and pressed against the inwardly extending rim of the member, I have found that such contacting means subjects the bulb wall to stresses which are oftentimes sufficiently great to cause cracking of the bulb wall. Therefore in accordance with a further teaching of my invention, I provide an outwardly extending projection II electrically associated with the member 9 to which electrical connection may be made, the extension II being wholly within the cup-shaped member 9 so that it is fully protected from injury or mechanical shock.

Still further in accordance with my invention the outwardly extending projection. I I is assembled with the cup-shaped member 9 in such a manner that when sealed into the bulb wall little or no stress is applied to the bulb wall because of the i e-enforcing effect produced by attachment of the two parts 9 and II. More specifically the extending projection Il comprises a base portion I3, a tubular portion I4 and a bulbous portion IS. The base portion I3 is welded or otherwise affixed to the cup-shaped member 9, the base portion being'of such diameter that a recessed annular welding tool may be applied over the tubular and bulbous portions but of insuiilcient diameter to extend close to the area of the member 9 to which the glass of the bulb I is sealed. More particularly an annular section I6 of the member 9 is neither covered on one side by the base portion I3 nor the glass of the bulb I. I have found that when the base portion I3 is of suillcient diameter to overlap the portion of the member 9 which is sealed to the glass, a differential expansion may occur which subjects the glass to mechanical stress with resultant failure of the glass-tometal seal.

The material of the member 9 is preferably of chrome-iron when the seal is to be made to conventionally used soft glass although the member 9 may be of any other metal havin the desired coefficient of expansion to match or substantially match that of the glass of the bulb I.

I have shown in Figure 2 means to make contact with the extension II comprising a contact clip II of resilient material which may be slipped over the bulbous portion I5 and into electrical contact therewith. The contact clip I I may have two leaves as shown or may be provided with three or four leaves to provide additional bearing area between the clip and the bulbous portion I5. To protect the user against relatively high voltages applied to the clip I! and to facilitate making contact with the exension l I, I provide a cover or housing [8 of insulating material enclosing the clip I1 and having an annular flange portion I9 enclosing the contacting portion of the clip I1. I have found that contact may be made between the bulbous portion I 5 and clip II more readily if the flanged portion l9 extends beyond the end of the clip I'I so that upon starting engagement, the flanged portion I9 comes into contact with the cup-shaped member 9 followed by engaging contact between the extension II and the clip I I. Thus, when the housing I8 and the clip II are in operating position, the annular flange portion I9 extends within the cup-shaped member 9, the housing [I being of such diameter that it projects over the member 9 protecting it from accidental contact and thereby preventing electrical shock to the user.

I have shown in Figure 3 a modified form of extension welded or otherwise afllxed to the cupshaped member 9. In the showing of Figure 3 the extension I I is preferably apertured, contact being made by an internally fitting clip l'l' which is resilient and, following insertion within the extension I I, expands making good electrical contact therewith. The clip housing I8, Figure 3, is likewise of insulating material provided with an annular flange portion I9 of suflicient length to engage the member 9 and guide the clip I I within the aperture of the extension II. As shown, the extension I I is likewise provided with a flange of limited diameter to provide an annular section which is neither covered by th base portion of the extension nor by the glass of the bulb I, thereby preventin introduction of strains which would otherwise occur because of diflerences in the eflective thickness of the member I.

ode ray tube structure.

Referring again to Figure 1 it will be appreciated that other uses than as a contact to deflection plates may be made of my improved means for providing electrical contact to cath- For example, electrical contact may be made to the electrically conductive coating 20 by the use of a cup-shaped member provided with an extending projection as shown at 2|. The cup-shaped member and extending projection as shown in 2| are -assembled and sealed into the wall of the bulb I at the desired location prior to application of the conductive coating 20 so that when this coating is applied, it extends over the convex side of the cup-shaped member thereby making good electrical contact therewith.

It will be appreciated that my means for providing electrical contact with electrode structure may be adapted to other uses than those shown where a lead extending from a bulb wall is undesirable and that my invention is particularly useful in a construction wherein a deflection coil is slipped over the contacts into an operating position. Therefore, while I have described only a few applications of my improved contact, it will be appreciated that it is equally useful on tubes of diii'erent types and that various modifications in my improved structure may be made without departing from the scope of the appended claims.

I claim:

1. An electrical'contact assembly comprising a metal cup, 9. projection attached to the bottom of said cup of insufficient length to extend beyond the rim of said cup, a contacting clip adapted to make electrical contact with said projection and insulating means surrounding said clip of sufiicient length to extend within said cup when said clip is in contact making position with said projection.

2. An electrical contact assembly comprising a metal cup, a projection of insufficient length to extend materially above the rim of said cup attached to the bottom of said cup, a contacting clip adapted to engage said projection and an insulating member surrounding said clip of sufflcient length to guide said clip into contact making position with said projection by bearing on the side walls of said metal cup.

3. In combination with an envelope enclossealed to the wall of said envelope and forming a portion thereof the bottom portion of said cup being out of contact with said envelope wall, a metal projection of insufilcient length to extend materially beyond the rim of said cup .afilxed to the bottom portion of said cup, the area of said cup opposite that bearing said projection being exposed to the interior of said envelope.

4. In combination with a glass envelope enclosing electrode structure, an electrical contact assembly comprising an imperforate metal cu having its rim portion sealed to said envelope the bottom of said cup being unsupported by said envelope and a metal projection in said cup afllxed to a small area centrally located in the bottom of said cup allowing a portion of the bottom of said cup to neither support said projection nor to be supported in direct contact with said envelope.

5. An electric discharge device comprising an envelope, a cup-shaped metal insert forming a small portion of the wall of said envelope, the bottom of said insert being exposed to the inside of said envelope, a contact projection aflixed ing structure to which electrical connection must be made, an electrical contact assembly comprising an imperforate metal cup having its rim centrally of said insert of insufiicient length to extend materially above the rim thereof, elec trode structure within said envelope and resilient means between electrode structure and the exposed portion of said insert to make electrical contact therebetween.

6. An electrical contact assembly comprising a metal cup, a projection within and extending from the bottom of said cup, said projection being of insufficient length to extend materially beyond the rim of said cup, a contacting clip adapted to make resilient electrical contact with said projection and insulating means surrounding said clip and extending slightly beyond said clip so as to extend within said cup when said clip is in contact-making position with said projection.

7. An electric discharge device comprising a glass envelope, a cup-shaped metal insert forming a small portion of the wall of said envelope, the bottom of said insert being exposed to the inside of said envelope, means within said cupshaped insert to make electrical contact thereto, electrode structure within said envelope and resilient means within said envelope and between said electrode structure and the exposed pcrtirm 05' said insert to make electrical contact therebetween.

MCLAUGHLIN. 

